The present invention relates to a scroll compressor.
Scroll compressors are known in the art. For example, Japanese Patent Laid-Open Publication No.59-65586 discloses a scroll compressor comprising paired fixed and movable scrolls, the fixed scroll of each pair having an end plate provided with a scroll body projecting from the end plate and the movable scroll of each pair having an end plate provided with a scroll body projecting from the end plate, wherein the movable scroll meshes with the fixed scroll to form a plurality of operation chambers between them and revolves relative to the fixed scroll to compress gas in the operation chambers, characterized in that two pairs of fixed and movable scrolls are disposed with back faces of the end plates of the fixed scrolls opposite each other, a main shaft for revolving the movable scrolls passes through the two pairs of fixed and movable scrolls to operatively engage the movable scrolls, and an outlet chamber is disposed between the end plates of the fixed scrolls.
In this known scroll compressor, the main shaft is supported at opposite ends by a housing accommodating the two pairs of fixed and movable scrolls. In the ordinary conventional scroll compressor comprising a pair of fixed and movable scrolls, and a main shaft operatively engaging the movable scroll at its one end, the main shaft is supported at its the other end by a housing accommodating the fixed scroll, the movable scroll and the main shaft. Therefore, the scroll compressor of Japanese Patent Laid-Open Publication No.59-65586 has advantages over the ordinary conventional scroll compressor, including that swirling of the main shaft is restrained, and vibration and noise due to such swirling of the main shaft are restrained.
However, the scroll compressor of Japanese Patent Laid-Open Publication No.59-65586 has following disadvantages.
1. Two movable scrolls are independent of each other. Therefore, anti-rotation mechanisms disposed between the end plates of the movable scrolls and the housing accommodating the scrolls are exposed to thrust load due to the compression of gas in the compression chambers, which causes them to wear and shorten the service life of the compressor. Downsizing of the compressor is difficult because downsizing of the ant-rotation mechanisms exposed to the thrust load is difficult
2. Also owing to the fact that two movable scrolls are independent of each other, adjustment of axial space between the fixed scroll and the movable scroll of one of the two pairs of fixed and movable scrolls must be carried out independently from the adjustment of axial space between the fixed and movable scrolls of the other of the two pairs of fixed and movable scrolls.
3. The main shaft operatively engages the movable scrolls at the central portions of the scroll bodies. Therefore, heat generated by bearings disposed at the operative engagement points is hard to disperse. As a result, the bearings are liable to heat and the service lives of the bearings are liable to become short.
4. No partition is disposed between bearings at the opposite ends of the main shaft and inlet chambers. Moreover, no partition is disposed between bearings at the operative engagement points and the inlet chambers. Therefore, gas taken into the inlet chambers is contaminated with lubricating oil in the bearings and the discharged gas is contaminated with lubricating oil. Therefore, the scroll compressor is not suitable for the compression of clean gas.
5. Also owing to the fact that no partition is disposed between bearings at the opposite ends of the main shaft and inlet chambers and no partition is disposed between bearings at the operative engagement points and the inlet chambers, gas heated by the hot bearings and increased in specific volume is taken into the operation chambers. As a result, flow rate of discharged gas from the scroll compressor is really low.
6. The bearings at the opposite ends of the main shaft and the bearings at the operative engagement points are disposed in substantially closed spaces. Therefore, heat generated by the bearings is hard to disperse, the bearings are liable to heat, and service lives of the bearings are liable to become short.
Therefore, the object of the present invention is to overcome the foregoing problems by providing a scroll compressor comprising paired fixed and movable scrolls, the fixed scroll of each pair having an end plate provided with a scroll body projecting from the end plate and the movable scroll of each pair having an end plate provided with a scroll body projecting from the end plate, wherein the movable scroll meshes with the fixed scroll to form a plurality of operation chambers between them and revolves relative to the fixed scroll to compress gas in the operation chambers, characterized in that two pairs of fixed and movable scrolls are disposed with back faces of the end plates of the fixed scrolls opposite each other, a main shaft for revolving the movable scrolls passes through the two pairs of fixed and movable scrolls to operatively engage the movable scrolls, and an outlet chamber is disposed between the end plates of the fixed scrolls.
In accordance with the present invention, there is provided a scroll compressor comprising paired fixed and movable scrolls, the fixed scroll of each pair having an end plate provided with a scroll body projecting from the end plate and the movable scroll of each pair having an end plate provided with a scroll body projecting from the end plate, wherein the movable scroll meshes with the fixed scroll to form a plurality of operation chambers between them and revolves relative to the fixed scroll to compress gas in the operation chambers, characterized in that two pairs of fixed and movable scrolls are disposed with back faces of the end plates of the fixed scrolls opposite each other, the movable scrolls are integrally connected with each other, a main shaft for revolving the movable scrolls passes through the two pairs of fixed and movable scrolls to operatively engage the movable scrolls, and an outlet chamber is disposed between the end plates of the fixed scrolls.
In the present scroll compressor, the two movable scrolls integrally connected with each other bear the thrust load accompanying the compression of gas in the operation chambers. Therefore, anti-rotation mechanisms disposed between the end plates of the movable scrolls and a housing accommodating the scrolls and the main shaft do not bear the thrust load. As a result, wear of the anti-rotation mechanisms is minimized and the shortening of the service life of the compressor is minimized. Being free from the thrust load, the anti-rotation mechanisms can be downsized. As a result, the compressor can be downsized.
In the present scroll compressor, the two movable scrolls are integrally connected with each other. Therefore, axial spaces between the fixed scrolls and the movable scrolls of the two pairs of fixed and movable scrolls can be adjusted by a single operation.
According to a preferred embodiment of the present invention, the main shaft operatively engages the movable scrolls at the back faces of the end plates of the movable scrolls.
When the main shaft operatively engages the movable scrolls at the back faces of the end plates of the movable scrolls, the operative engagement points are close to the housing accommodating the two pairs of fixed and movable scrolls. Therefore, heat generated by the bearings at the operative engagement points is able to disperse to outside the compressor. As a result, heating of the bearings at the operative engagement points is suppressed and shortening of the service lives of the bearings is minimized.
According to another preferred embodiment of the present invention, the movable scrolls abut against a housing accommodating the two pairs of fixed and movable scrolls through seal members at peripheral portions of the back faces of the end plates.
Anti-rotation mechanisms and bearings of the main shaft are disposed between the back faces of the end plates of the movable scrolls and the portions of a housing opposite the back faces of the end plates. When the movable scrolls abut against the portions of the housing through seal members at peripheral portions of the back faces of the end plates, partitions are formed between the inlet paths of the compressor formed at the side of the scroll bodies of the movable scrolls and the anti-rotation mechanisms, the bearings of the main shaft and the bearings at the operative engagement points. Therefore, powder of abraded materials of the anti-rotation mechanisms and bearings, grease, etc. are prevented from entering into the operation chambers and discharged gas from the compressor is prevented from contamination by powder of abraded materials of the anti-rotation mechanisms and bearings, grease, etc. As a result, the scroll compressor in accordance with the present invention can be used for compression of clean gas.
Partitions are formed between the inlet paths of the compressor formed at the side of the scroll bodies of the movable scrolls and the anti-rotation mechanisms, the bearings of the main shaft and the bearings at the operative engagement points. Therefore, gas heated by the anti-rotation mechanisms and bearings to be increased in specific volume is prevented from entering into the operation chambers. As a result, the flow rate of discharged gas from the compressor is prevented from substantial decrease.
According to another preferred embodiment of the present invention, difference in phase angles of 180 degrees is present between scroll bodies of the fixed scrolls.
When difference in phase angles of 180 degrees is present between the scroll bodies of the fixed scrolls, difference in phase angles of 180 degrees is generated between pulsations of discharged gases from the two pairs of fixed and movable scrolls. Therefore, the pulsations of discharged gases cancel each other and generation of noise due to the pulsation of discharged gas is prevented. Moreover, difference in phase angles of 180 degrees is generated between pulsations of intake gases into the two pairs of fixed and movable scrolls. Therefore, the pulsations of intake gases cancel each other and generation of noise due to the pulsation of intake gas is prevented.
According to another preferred embodiment of the present invention, the relation r0 greater than r greater than (r0xe2x88x920.3 mm) is present between a revolution radius r of the movable scrolls determined by the anti-rotation mechanisms and a revolution radius r0 of the movable scrolls determined by the scroll bodies of the fixed scrolls and the scroll bodies of the movable scrolls.
When r0 greater than r, interferences between the scroll bodies of the fixed scrolls and the scroll bodies of the movable scrolls are prevented and generation of powder of abraded members due to such interferences is prevented. When r greater than (r0xe2x88x920.3 mm), decrease of compression efficiency is prevented.
According to another preferred embodiment of the present invention, the housing is provided with air holes opposite the back faces of the end plates of the movable scrolls.
When the housing is provided with air holes opposite the back faces of the end plates of the movable scrolls, spaces formed between the back faces of the end plates of the movable scrolls and the housing communicate with the atmosphere through the air holes. Therefore, heat generated by the anti-rotation mechanisms, bearings, etc. disposed in the spaces disperses to the atmosphere through the air holes. As a result, decrease of compression efficiency due to thermal deformation of movable scrolls is prevented and shortening of the service lives of the anti-rotation mechanisms, bearings, etc. due to loss of grease, thermal deformation, etc. is prevented.
According to another preferred embodiment of the present invention, the end plates of the movable scrolls are provided with cooling fins at their back faces.
When the end plates of the movable scrolls are provided with cooling fins at their back faces, cooling efficiency of the movable scrolls, anti-rotation mechanisms and bearings is enhanced.
According to another preferred embodiment of the present invention, the main shaft is provided with balancing weights and axial fans connected to the balancing weights at its portions extending between the back faces of the end plates of the movable scrolls and the portions of the housing opposite the back faces of the end plates.
According to another preferred embodiment of the present invention, the main shaft is provided with balancing weights and centrifugal fans connected to the balancing weights at its portions extending between the back faces of the end plates of the movable scrolls and the portions of the housing opposite the back faces of the end plates.
When balancing weights are provided with axial fans or centrifugal fans, cooling efficiency of the movable scrolls, anti-rotation mechanisms and bearings is enhanced.
According to another preferred embodiment of the present invention, the centrifugal fans are provided with deflectors for directing the discharged air parallel to the main shaft.
When the centrifugal fans are provided with deflectors for directing the discharged air parallel to the main shaft, the flow rate of air colliding against the end plates of the movable scrolls increases and cooling efficiency of the movable scrolls is enhanced.
According to another preferred embodiment of the present invention, a cooling chamber communicating with the space outside the housing is disposed between the end plates of the fixed scrolls.
End plates of the fixed scrolls are cooled by airflow induced in the cooling chamber. As a result, thermal deformation of fixed scrolls is restrained and decrease of compression efficiency due to such thermal deformation of fixed scrolls is suppressed.
According to another preferred embodiment of the present invention, the end plates of the fixed scrolls and movable scrolls are disks with their peripheral portions partially cut off arcuately.
The end plates of fixed scrolls and movable scrolls are usually disks. Portions of the disks radially outside the scroll bodies serve no function. Partial cutting off of the functionless portions of the disks enables downsizing of the compressor.
Further objects, features and advantages of the present invention will become apparent from the Detailed Description of the Preferred Embodiment when read in conjunction with the accompanying drawings.